OXIDATIVE AMMONOLYSIS OF ALKYLPYRIDINES

Abstract: A process for the preparation of a highly selective catalyst and its application in the production of cyanopyridines by oxidative ammonolysis of alkylpyridines is described. The catalytic composition is defined by the formula: Va Tib Zrc Ox, wherein a is 1, b is 7.5 to 8, c is 0 to 0.5, x represents the number of oxygen atoms necessary to satisfy the valency requirements of the elements present.

Description: Oxidative ammonolysis of alkylpyridines This invention relates to a process for the preparation of a highly selective catalyst for the production of cyanopyridines by oxidative ammonolysis of alkylpyridines and to a process for the preparation of cyanopyridines. The invention is especially directed to the production of 3-cyanopyridine or cyanopyridine derivatives which are important precursors for nicotinic acid or nicotinic acid amide. Nicotinic acid or nicotinic acid amide are essential vitamins of the B-complex. Oxidative ammonolysis of alkylpyridines is well known in the art. A great variety of catalyst systems and processes there to have been disclosed but so far no process is known which can satisfy the needs of a commercial process on technical scale. Reference is made to British patent GB 1 317 064 wherein a mixed oxide catalyst of vanadium oxide and titanium oxide having a molar ratio of 1 :0.6 to 1 :32 is disclosed for the oxidative ammonolysis of alkylpyridines. The maxiumum yield of cyanopyridine achieved for the conversion of 3-methylpyridine was 89% (example 42; V2θ5:Tiθ2 = 1 : 16) and for the conversion of 2-methyl-5-ethylpyridine 61% (example 54; V 2 O 5 :TiO 2 = 1:4). The results are obtained with this known process cannot satisfy especially with respect to selectivity, yield, and feed rates of alkylpyridines. The object of the present invention therefore is to provide a highly selective ammonoxidation catalyst and an improved process for the conversion of alkylpyridines by oxidative ammono¬ lysis. The drawbacks could be overcome by a highly active catalyst prepared according to claim 1 and with an oxidative ammonolysis process according to claim 7. The preparation of the catalytic composition defined by the formula V a Tib Z f c Oχ wherein a is 1 b is 7.5 to 8 c is 0 to 0.5 x represents the number of oxygen atoms necessary to satisfy the valency requirements of the elements present follows according to claim 1 the steps of coprecipitating a solution of a $ + - and of a Ti"^ + - and optionally of a Zr^ + -compound in water with a solution of ammonia in water, by a subsequent exposure of the precipitate to a drying treatment and to a heat treatment and by a shaping step in order to bring the catalytic composition in a suitable catalyst form. Suitable sources of the titanium component are preferably water soluble Ti^ + -compounds such as titaniumchloride, titaniumbromide, titaniumnitrate or organic Ti-compounds such as Ti- tetraalkylcompounds. Suitable sources of the vanadium component are water soluble V-^ + -compounds, for example ammoniummetavanadate. A suitable source for the zirconium component is preferably a water soluble Zr^ + -compound such as zirconiumoxychloride. The coprecipitation takes place by a simultaneous mixing of the dissolved catalyst components with an ammonia water solution in such a manner that after the coprecipitation the pH of the liquid is between 8 and 9. The precipitate formed can then be separated by known means and afterwards either first dried, preferably in an air stream at temperatures between 120°C and 140°C, or directly exposed to a heat treatment at temperatures between 360°C to 400°C, preferably in presence of air. Then a common shaping step can follow in order to suitably mould the catalyst. Preferably tablets are formed which are advantageously exposed to a further heat treatment at temperatures between 740°C and 850°C in the presence of air The ready prepared catalytic composition can then be loaded into the reactor, wherein after an activation phase under reaction conditions, it is able to demonstrate its properties with respect to high activity and selectivity at high loads of the alk lpyridine, and with respect to long life¬ time. Preferred catalytic composition are: Tig O x v τi 7.5 Zr 0 .5 O x V τ '7.5 Zro. i25 O x whrein x is as defined before. The most preferred catalytic composition is: V Tig o x wherein x is as defined before The process of the present invention is applicable for the conversion of a wide variety of alkylpyridines to cyanopyridines. Suitable alkylpyridines are e.g. 3-methylpyridine, 3-ethyl- pyridine, 2-methyl-5-ethylpyridine, 2,5-dimethylpyridine and 2-methyl-5-vinylpyridine. Most preferred alkylpyridines are the 3 -methyl pyridine and the 2-methyl-5-ethylpyridine. The following process conditions have been proved to be suitable. The gaseous feed is composed of the respective alkylpyridine, of an oxygen containing gas, ammonia and water vapour. In general air will be used as oxygen containing gas. Thus air offers the advantage that oxygen is already diluted with inert components. In case of the conversion of 3-methylpyridine to 3 -cyanopyridine the gaseous feed is expediently composed of 3-methylpyridine, air (calculated to O2), ammonia, water vapour in a molar ratio from 1 :7:3:3 to 1 :40: 10:45. Preferably ratio ranges from 1: 10:4: 10 to 1 :30:7:30. In case of the conversion of 2-methyl-5-ethylpyridine to 3 -cyanopyridine and depending on the reaction conditions also to 2,5-dicyanopyridine the gaseous feed is expediently composed of 2-methyl-5-ethylpyridine, air (calculated to O2 ammonia, water vapour in a molar ratio from 1 : 15:5:20 to 1 :70:40: 140. The temperature in the reaction zone of the catalyst ranges as a rule between 330°C and 440°C , preferably between 350°C and 410°C. Due to the stable catalyst characteristics with respect to life-time, the process according to the present invention can run continously over a long time on a large-scale basis. The maximum molar yields achievable reach about 95% to 97% for the conversion of 3- methyl pyridine and about 75% for the conversion of 2-methyl-5-ethylpyridine. The resulting cyanopyridines, i.e. the 3-cyanopyridine and/or the 2,5-dicyanopyridine, can be directly converted to nicotinic acid by a common hydrolysis treatment with a base. A nicotinic acid yield of up to 95%, based on 3-methylpyridines. can accordingly be reached. Examples: catalyst preparation a) V Tig O x catalyst: 690.4 g (3.64 mol) titaniumchloride is slowly mixed with 400 ml water at a temperature of about 60°C to 65°C. Water is added to a total volume of 800 ml. In a separate vessel 53.19 g (0.45 mol) ammoniummetavandate is dissolved in 850 ml water and 300 ml of a solution of ammonia in water under reflux conditions. During this procedure ammonia is introduced into the solution. The solution containing the V-compound is added to the Ti-solution at about 80°C to 85°C. Water is added to a total volume of 4 litres. In a cylinder reactor with mixing elements 670 ml of the Ti-V-solution having a temperature of 80°C to 85°C is mixed with 670 ml of a 5.2 % solution of ammonia in water. The coprecipitate formed is filtered off, washed with water and then dried in an air stream at a temperature of 120°C to 140°C. The resulting powder is then treated in a furnace at a temperature of 360°C in presence of air over 2 hours, subsequently milled in a ball mill and finally moistened with water and moulded to tablets with dimensions 4 x 4 mm. The tablets are treated in a muffle furnace in presence of air at a temperature of 740°C for 2 hours. Fresh prepared catalyst is then activated under oxidative ammonolysis conditions with 3- methylpyridine. b) V Ti 5 ZΓQ 5 O x catalyst: The V-Ti-solution is prepared as mentioned under a) In a separate vessel 73.27g (0.23 mol) zirconiumoxychloride 8 H2O is dissolved in 600 ml of water at temperatures between 40°C and 45°C. The coprecipitation is performed in a corresponding manner as mentioned under a) by mixing 625 ml of the Ti-V-solution, 100 ml of the Zr-solution and 725 ml of the respective solution of ammonia in water. The further work up of the resulting precipitate is performed as mentioned under a). V Ti 5 ZΓQ 125 O x catalyst: The procedure of example b) was repeated except that for the coprecipitation, 625 ml of the Ti-V-solution, 25 ml of the Zr-solution and 650 ml of the respective solution of ammonia in water are mixed. Process example 1 : 220 cm 3 of the activated V Tig O x catalyst were loaded into a tube reactor made of stainless steel (internal diameter 20 mm, length 1200 mm). A gaseous mixture of the reagents consisting of 3-methylpyridine (3-MP), air, ammonia and water vapour was passed through the catalyst layer for 150 hours at a temperature of 385°C with a feeding rate of 103.6 gHlr 1 3-MP, 2727 1 l^h^air, 113.8 gT " lh " l ammonia and 336.4 gHh"l water vapour. Molar ratio of the feed was: 3-MP:air(O 2 ):NH 3 :H 2 O = 1 :22.9:6.0:16.8. 114 g 3-MP was converted during 5 hours. The conversion was complete. 1 19.5 g 3- cyanopyridine was obtained corresponding to a yield of 93.7% from theory. The output of 3- cyanopyridine accordingly was 108 gl _1 h-l. Hydrolysis with KOH (reflux for 2 hours) gave 143.2 g (95% of theory) nicotinic acid. example 2: The same catalyst as described in example 1 was used. A mixture of the reagents consisting of 2-methyl-5-ethylpyridine (MEP), air, ammonia and water vapour was passed through the catalyst layer at a temperature of 395°C. The molar ratio of the feed was: MEP:air (02):NH3:H 2 O = 1 :25: 19:67. 155 g MEP was converted over 10 hours giving 93.2 g 3-cyanopyridine corresponding to a yield of 70.5% from theory. The ouput of 3 -cyanopyridine accordingly was 42.8 gl" 1 !."' 1 . Hydrolysis with KOH gave nicotinic acid in a yield of 72% from theory. example 3: The same catalyst ( 140 cm 3 ) as described in example 1 was used. The same reagents as described in example 2 were passed through the catalyst layer at a temperature of 400°C. The molar ratio of the feed was MEP air (O2) NH3 H2O = 1 16 14 30 53 2 g MEP was converted over 5 hours giving 19 7 g 2,5-dιcyanopyndιne (34 8% from theory) and 23 0 g 3 -cyanopyridine (50 3% from theory) Hydrolysis with KOH gave nicotinic acid in a yield of 85 4% from theory example 4 100 cm 3 of the activated V T17 5 ZΓQ 5 O x catalyst was loaded into the tube reactor mentioned in example 1 A gaseous mixture of 3-methylpyridine (3-MP). air, ammonia and water vapour was passed through the catalyst layer at a temperature of 375°C with a feeding rate of 225 gl^h" 1 3-MP, 344.1 gl^h" 1 air, 111 gl^h" 1 NH3 and 980 gl^h" 1 H 2 0 112.3 g 3-MP was converted over 5 hours giving 92.1 g 3 -cyanopyridine (73 2% from theory) and 21.8 g nicotinamide (14 8% from theory) Hydrolysis with KOH gave 138 7 g (93 3% from theory) nictoinic acid example 5 The same catalyst as described in example 4 was applied for a gaseous feed containing MEP instead of 3-MP The temperature of the catalyst layer was 370°C The feeding rate was 80 gl-ϊh-l MEP, 1225 1 air, 180 g NH 3 and 1130 g H 2 O. 48 g MEP was converted over 6 hours giving 3 6 g 2,5-dicyanopyridine (7% from theory) and 28.9 g 3 -cyanopyridine (70% from theory) Hydrolysis with KOH gave nicotinic acid in a yield of 79.9% from theory example 6 100 cm 3 of the activated V T17 5 ZΓQ J25 Oχ catalyst was applied in the same manner as in example 4 1 12 5 g 3-MP was converted over 5 hours giving 100 8 g 3-cyanopyπdιne (80 1% from theory) and 17 g nicotinamide ( 1 1 4% from theory) Hydrolysis with KOH gave 139 g (93 3% from theory) nicotinic acid example 7 The same catalyst (100 cm 3 ) as described in example 1 was applied for a gaseous feed containing 3-ethylpyridine (3-EP) The temperature of the catalyst layer was 380°C- The feeding rate was 150 gHh' 1 3-EP, 3600 1 l^h" 1 air, 167 gl^h" 1 NH3 and 252 gl^h" 1 H 2 O 75 g 3-EP was converted over 5 hours giving 66.5 g 3-cyanopyridine (91.2% from theory) example 8 The same catalyst (100 cm 3 ) as described in example 1 was applied for a gaseous feed contai¬ ning 2,5-dimethylpyridine (2,5 DMP) The temperature of the catalyst layer was 400°C The feeding rate was 102 gl' -h' 1 2,5 DMP, 2095 1 l^h" 1 air, 227 gl^h" 1 NH3 and 650 gHh-l H 2 O 52 g 2,5 DMP was converted over 5 hours giving 18.8 g 2,5-dicyanopyridine (30 6% form theory) and 28 8 g 3 -cyanopyridine (58 1% from theory) Hydrolysis with NH3 in an autoclave gave nicotinic acid in a yield of 87 9% form theory. example 9" The same catalyst (100 cm 3 ) as described in example 1 was applied for a gaseous feed containing 2-methyl-5-vinylpyridine (2-MVP: The temperature of the catalyst was 400°C. The feeding rate was: 1 13.4 gl^h" 1 2-MVP, 2095 1 l^h" 1 air, 227 gl^h" 1 NH3 and 750 gl-lh- 1 H 2 O. 57 g 2-MVP was converted over 5 hours giving 23.4 g 2,5-dicyanopyridine (37.9% form theory) and 24.4 g 3 -cyanopyridine (48.9% form theory). Hydrolysis with NH3 in an autoclave gave nicotinic acid in a yield of 86.3% from theory. example 10: The same catalyst as described in example 1 (710 ml) was loaded into a stainless steel tube reactor (internal diameter 21 mm, length 3 m). A gaseous mixture of the reagents consisting of 3-methylpyridine (3-MP), air, ammonia and water was passed through the catalyst bed for 1350 hours at a temperature of 385°C with a feeding rate which varied between 100 and 150 gHh"* 3-MP. The molar ratio of the feed 3- MP: air (O2): ammonia: water varied between 1 :5.2: 10: 13 and 1 :5.2: 16: 15. 107 kg 3-MP was converted to 108 kg 3-cyanopyridine. The conversion was 97%. the molar yield corresponded to 91% and the selectivity 93.5%. example 1 The V Tig O x catalyst was prepared according to example a), catalyst preparation- but with the difference that the heat treatment of the tablets was conducted at a temperature of 850 °C for 2 hours. 140 cm 3 of this activated catalyst was loaded into the tube reactor mentioned in example 1. A gaseous mixture of 2-methyl-5-ethylpyridine (MEP), air, ammonia and water vapour was passed thorough the catalyst layer at a temperature of 375 °C. The molar ratio of the feed was: MEP: air (O2):NH3:H2O = 1 :34: 10:41. 53.2 g MEP was converted over 5 hours giving 22.8 g 2,5-dicyanopyridine (40.2% from theory) and 22.5 g 3-cyanopyridine (39.7% from theory). Hydrolysis with KOH gave nicotinic acid in a yield of 90.2% from theory. table 1 oxidative ammonolysis of 3-methylpyridine (3-MP) with V Tig O catalyst feed 3-MP feed composition (mol) tempe¬ yield 3-cyanopyridine service example g / 1 cat. rature life of cat. per hour °C h xn va n 3-MP air NHi H O % g/1 cat. / h m 12 101 4 23 5 6 1 17 380 91 103 2 120 CO 13 127 3 22 4 7 9 15 7 385 91 129 5 135 m 14 140 2 23 5 6 1 30 2 390 92 3 144 5 175 c 15 150 2 22 4 6 2 30 5 390 91.4 153 3 190 ro σ table 2 oxidative ammonolysis of 2-methyl-5-ethylpyridine (MEP) with V Tig O x catalyst feed feed composition (mol) tempe¬ yield 3-cyanopyridine (CP) / service example MEP rature 2,5-dicyanopyridine (DCP) life of g 1 cat. °C cat CO per hour h CO MEP air NH 3 H7O CP % g/1 cat./h DCP % CO 16 20.9 59 35 136 350 75 13.5 145 m m 17 25 50 30 1 16 350 70 15 200 18 50 za 19 18 74 360 70 30 6 520 19 70 7 25 19 67 370 70.5 42.8 12 560 ro CD

Claims: Claims' 1 Process for preparing a catalytic composition defined by the formula V a Ti]-, Zr c O x wherein a is 1 b is 7.5 to 8 c is 0 to 0.5 x represents the number of oxygen atoms necessary to satisfy the valency requirements of the elements present, by coprecipitating a solution of a $ + - and of a Ti * ^ + - and optionally of a Zr 4 " - compound in water with a solution of ammonia in water, followed by an exposure of the so-formed precipitate to a drying and heat treatment and by bringing the catalytic compositon in a suitable catalyst form. 2. Process according to claim 1 characterised in that the precipitate formed is either first dried in an air stream at a temperature between 120°C and 140°C, or directly exposed to a heat treatment at temperatures between 360°C and 400°C, then shaped into a suitable catalyst form, and finally exposed to a heat treatment at a temperature between 740°C and 850°C. 3 Catalytic composition obtainable by the process of claim 1 or 2 4. Catalytic composition according to claim 3 defined by the formula V Tig O x wherein x is as defined above. 5. Catalytic composition according to claim 3 defined by the formula V Ti 5 ZΓ Q 5 O x wherein x is as defined above. 6. Catalytic composition according to claim 3 defined by the formula V Tι~j 5 ZΓQ 125 O x wherein x is as defined above. 7. Process for the production of cyanopyridines by oxidative ammonolysis of alkylpyridines characterised in that a gaseous feed composed of an alkylpyridine, an oxygen containing gas, ammonia and water vapour is passed over a coprecipitated catalytic composition prepared according to claim 1 at a temperature between 330°C and 440'°C. 8. Process according to claim 7 characterised in that a catalytic composition of claim 4 is applied. 9. Process according to claim 7 characterised in that a catalytic composition of claim 5 is applied. 10. Process according to claim 7 characterised in that a catalytic composition of claim 6 is applied. 11. Process according to claim 7 to 10 characterised in that the alkylpyridine is selected from 3-methylpyridine, 3-ethylpyridine, 2-methyl-5-ethylpyridine, 2,5-dimethylpyridine and 2- methyl-5-vinylpyridine. 12. Process according to claim 1 1 characterised in that 3-methylpyridine or 2-methyl-5- ethylpyridine is selected. 13. Process according to claim 7 to 12 for the production of 3 -cyanopyridine by oxidative ammonolysis of 3-methylpyridine characterised in that a gaseous feed of the reactants 3- methylpyridine, oxygen containing gas (calculated to O2), ammonia and water vapour in a molar ratio from 1:7:3:3 to 1 :40: 10:45 is passed over the catalyst. 14. Process according to claims 7 to 12 for the production of 3-cyanopyridine by oxidative ammonolysis of 2-methyl-5-ethylpyridine characterised in that a gaseous feed of the reactants 2-methyl-5-ethylpyridine, oxygen containing gas (calculated to 02), ammonia and water vapour in a molar ratio from 1: 15:5:20 to 1:70:40:140 is passed over the catalyst.

Inventors: BELOVA NADEZHDA ANTONOVNA, CHUCK RODERICK JOHN, PIANZOLA DANIEL, STEPANOVA LIDIJA ANATOLJEVNA, SUVOROV BORIS VIKTOROVITCH, BELOVA, NADEZHDA ANTONOVNA, CHUCK, RODERICK, JOHN, PIANZOLA, DANIEL, STEPANOVA, LIDIJA ANATOLJEVNA, SUVOROV, BORIS VIKTOROVITCH
Applicants: BELOVA NADEZHDA ANTONOVNA, CHUCK RODERICK JOHN, INST OF CHEMICAL SCIENCE OF TH, LONZA AG, PIANZOLA DANIEL, STEPANOVA LIDIJA ANATOLJEVNA, SUVOROV BORIS VIKTOROVITCH, BELOVA, NADEZHDA ANTONOVNA, CHUCK, RODERICK, JOHN, INSTITUTE OF CHEMICAL SCIENCE OF THE NATIONAL ACAD, LONZA LTD., PIANZOLA, DANIEL, STEPANOVA, LIDIJA ANATOLJEVNA, SUVOROV, BORIS VIKTOROVITCH
Application year: 1994
Main classification: B01J23
IPC codes: B01J23, B01J37, C07D213